CN113832764A

CN113832764A - Thermo roll for a fiber web machine

Info

Publication number: CN113832764A
Application number: CN202110696214.7A
Authority: CN
Inventors: J·詹霍宁
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2020-06-24
Filing date: 2021-06-23
Publication date: 2021-12-24
Anticipated expiration: 2041-06-23
Also published as: CN113832764B; EP3929353A1; EP3929353B1

Abstract

The present invention relates to a heat roller. The heat roller (12) includes a hollow roller body (13) having a plurality of grooves (14) on an outer surface (15) thereof. Each groove (14) extends from one end of the roller body (13) to the other end. An axial bore (16) leading to the recess (14) is provided in the roller body (13). The thermo roll (12) further comprises a journal (17) having a conductor (18) extending to the axial bore (16) and being fixed to both ends of the roll body (13) by means of a plurality of bolts (19). Furthermore, the heat roller (12) comprises an outer jacket (21) which is frictionally fitted on the roller body (13) and the journal (17) and which closes the grooves (14) as a plurality of passages (22) for a heat transfer medium. Each axial bore (16) has an offset (23) leading to two adjacent grooves (14).

Description

Thermo roll for a fiber web machine

Technical Field

The invention relates to a thermo roll for a fiber web machine, comprising:

-a hollow roller body having a plurality of grooves on its outer surface, each groove extending from one end of the roller body to the other end, and axial bores in the roller body leading to the grooves;

-a journal having a conductor (product) extending to the axial bore and being secured to both ends of the roll body by a plurality of bolts; and

an outer jacket, which is friction-fitted (frictionally fitting) on the roller body and the shaft journal and which closes the grooves as a plurality of passages for the heat transfer medium.

Background

Finnish patent No. 122707 discloses a thermo roll of a fiber web machine. The thermo roll has a roll body with two journals. The axle journals are bolted to the roll body. In addition, the roller body has a groove and an outer sheath. Thereby forming a channel for the heat transfer medium. The shaft journals and the roller body have bores (bores) for the introduction and withdrawal of the heat transfer medium into and out of the channels. In practice, there is one axial bore per groove.

The diameter of the known roller body and the wall thickness of the roller body itself are large, because of the space required for the axial bores and the bolts. But the journal also weakens due to the bore. The journal must also be large. These characteristics make the entire heat roller large and heavy. This reduces the possibility of using the hot roll at a different location.

Disclosure of Invention

It is an object of the invention to provide a thermo roll for a fiber web machine which is simpler than before, in particular with a smaller diameter. The characteristics of the heat roller according to the invention are given by the present disclosure. The thermo roll, in particular the roll body and the shaft journal, has smaller bore holes than before. Thereby making small journals possible. Simultaneously, the wall thickness of the roller body can be smaller. Furthermore, by arranging the bore holes in a new way, the wall thickness of the roller body can be minimized.

The invention relates to a thermo roll for a fiber web machine, comprising: a hollow roller body having a plurality of grooves on an outer surface thereof, each groove extending from one end of the roller body to the other end, and having an axial bore in the roller body leading to the groove; a journal having a conductor extending to the axial bore and fixed to both ends of the roll body by a plurality of bolts; and an outer jacket frictionally fitted over the roller body and the journal, and enclosing the grooves as a plurality of passages for a heat transfer medium; wherein each axial bore has an offset to two adjacent grooves.

Preferably, each conductor comprises a radial bore between two adjacent grooves, the corresponding axial bore being arranged to open into the radial bore.

Preferably, there is a bolt between the two radial bores.

Preferably, the axial bore and the bolt are on substantially the same radius relative to the centre of the journal.

Preferably, there is a neck between the grooves, the axial bore being located at the neck.

Preferably, each bolt is located at the neck, adjacent to the axial bore.

Preferably, a heat insulating bush is provided in the axial bore, with an air gap (air gap) between the axial bore and the heat insulating bush.

Preferably, the width of the neck is the same as the width of the groove.

Preferably, the depth of the grooves decreases in the flow direction of the heat transfer medium.

Preferably, the outer sheath has a thickness of 20-40 mm.

Preferably, the wall thickness of the hollow roller body is 60-80 mm.

Preferably, there is an additional insulation bushing in the radial bore, with an air gap between the radial bore and the additional insulation bushing.

Preferably, a central bore is provided in the journal, and a flow diverter is arranged inside the central bore at the beginning of the radial bore.

Preferably, both journals and their conductors are identical for conveying the heat transfer medium from one journal to the other journal via said channels.

Preferably, inside the central bore and the journal there is a central tube for the supply or return of the heat transfer medium.

Drawings

The present invention is described in detail below with reference to the attached drawing figures, which show some embodiments of the invention, wherein:

FIG. 1 shows a schematic side view of a part of a fiber web machine equipped with a thermo roll according to the invention;

FIG. 2a shows a schematic cross-sectional view of a thermo roll according to the invention;

FIG. 2b shows a partial cross-sectional view of a thermo roll according to the invention;

FIG. 3 shows a schematic view of a thermo roll according to the invention as seen from a thermo roll head;

fig. 4 shows a part of a thermo roll without an outer jacket according to the invention.

Detailed Description

Fig. 1 shows a part of a fiber web machine in a side view. Here a calender 10 with a stack of rolls 11(stack of rolls). At least a part of these rolls is a thermo roll 12. In a calender, the thermo roll is heated by a heat transfer medium, which is hot water or oil or another hot fluid. By heating, the properties of the fibrous web (e.g. paper) can be improved. Furthermore, the guide roll may be a thermo roll. Typically, the heated rolls are contacted with other rolls or heated rolls in a nip. The thermo roll according to the invention can also be used elsewhere where it is desired, for example in the dryer section of a fiber web machine.

FIG. 2a shows a cross section of the heat roller 12 according to the invention. The thermo roll 12 is intended for a fiber web machine. The heat roller 12 includes a hollow roller body 13 having a plurality of grooves 14 on an outer surface 15 thereof. The recess 14 is shown in detail in fig. 4. The grooves can extend in the axial direction of the thermo roll, but can also extend, for example, at an angle or helically to avoid, inter alia, a jamming phenomenon (jamming phenomenon). Each groove 14 extends from one end of the roller body 13 to the other. In addition, axial bores 16 leading to the grooves 14 are provided in the roller body 13. The thermo roll further comprises a journal 17 with a conductor 18 extending to the axial bore 16. The journals 17 are fixed to the ends of the roller body 13 by means of a plurality of bolts 19. In fig. 2a two bolts 19 are shown, and in fig. 3 holes 20 for the bolts are shown. The thermo roll 12 further comprises an outer jacket 21 which is frictionally fitted over the roll body 13 and the axle journal 17. The friction fit is also referred to as an interference fit or press fit. The outer jacket 21 encloses the grooves 14 as a plurality of channels 22 for the heat transfer medium. In the embodiment shown in fig. 2a, the flow 25 of the heat transfer medium is shown by solid arrows. In the basic embodiment, the heat transfer medium is conveyed via the journal 17 to the axial bore 16 and from there into the groove 14 and finally out of the thermo roll via the other journal 17. The cross section of fig. 2a has two planes, which respectively show the recess 14 (upper side) with the axial bore 16 and the bolt 19 (lower side).

In the present invention, each axial bore 16 has an offset 23 leading to two adjacent grooves 14. In other words one axial bore hole ends in two adjacent grooves. This reduces the number of required boreholes by half. And meanwhile, the wall thickness of the roller body can be reduced. In practice the bore is so large that it enters (reach) at least partially into both recesses 14 (fig. 4). Here, the axial bore 16 is mainly in the neck 24 between the two grooves 14. Therefore, only one drilling (drilling) is needed, and the axial drilling holes entering the two adjacent grooves can be simply machined. Alternatively, a small axial bore may be made first, followed by two angled bores, each of which enters a groove.

Furthermore, the bolt is positioned in a new way. Advantageously, there is a bolt 19 between the two radial bores 29. In other words, there is one bolt every other neck. Advantageously, the axial bore 16 and the bolt 19 are substantially on the same radius with respect to the centre of the journal 17 (fig. 3). In this way, the thickness of the roller body can be minimized. Even so, there is still sufficient space for axial drilling and bolts. Only the holes 20 for the bolts are shown in fig. 3, not the bolts themselves. Here, there are necks 24 between the grooves 14, and the axial bores 16 and the bolts 19 are located in the necks 24. Furthermore, each bolt 19 is located adjacent to the axial bore 16 at the neck 24. It is thus possible to use bolts long enough to obtain a rigid fixation (rigid fixation). More generally, the distance between the bolt and the axial bore is substantially the same as the radius (radius) drawn through the centre of the hole for the bolt and the bore intersecting the periphery of the adjacent holes (errors).

As previously mentioned, the journal 17 has a conductor 18 extending to the axial bore 16. First, a central bore 25 passes through the journal 17. At the inner end of the central bore 25 there is an enlarged portion 26 which forms a cavity 27 when the central bore 25 is closed by a wall 28. Furthermore, each conductor 18 comprises a radial bore 29 between two adjacent grooves 14, the corresponding axial bore 16 being arranged to open into the radial bore 29. In other words, there is one radial bore per axial bore. When the number of axial bores is halved, the number of radial bores is also halved. Thereby, there is sufficient material between the radial bores so that the journal can withstand heavy loads.

After the outer sheath is installed, the radial bore is closed by the outer sheath. However, each radial bore 29 has a plug 30 ensuring tightness. The plug also serves as insulation. For the same purpose, an insulation bushing 31 is provided in the axial bore 16, with an air gap 32 between the axial bore 16 and the insulation bushing 31. The insulating bush 31 ends just before the recess (fig. 2 b). This allows as much heat as possible to end up in the grooves. The insulation blanket is replaceable and may have different sets of blankets with different diameters. Thereby, the flow rate of the heat transfer medium can be adjusted as desired.

By arranging the drill holes in a new way, there can be more grooves than before. Advantageously, the width of the neck 24 is the same as the width of the groove 14. Thereby allowing heat to be transferred uniformly and there is sufficient space to attach the bolt. Furthermore, the temperature of the outer sheath remains uniform, thereby improving the properties of the fiber web.

When the fluid flows in the grooves in only one direction, the depth of the grooves decreases in the direction of flow of the heat transfer medium. This equalizes the residence time of the fluid. Therefore, even if the heat transfer medium is supplied from only one end of the heat roller, the temperature of the heat roller can be uniform. If the flow rate of the heat transfer medium is sufficiently large, the temperature of the heat roller is kept uniform.

When positioning the axial bores and bolts according to the invention, the thermo roll can be optimized and minimized. In practice, the outer sheath 21 has a thickness of 20-40 mm. In this way, heat is transferred to the fiber web more efficiently. At the same time, the quality of the heat roller becomes smaller than before. Finally, it is still possible to grind the outer sheath by about 10 mm.

The maximum weight loss is achieved by reducing the wall thickness of the hollow roller body. According to this surprising idea, the wall thickness of the hollow roller body may be only 60-80mm, even for a hot roller of 6 meters length. Therefore, there is a high demand for actual nip pressure, not the space required for drilling and bolting. Thereby, the size of the heat roller can be minimized and optimized.

In small, for example 600mm diameter, hot rolls, the width of the grooves may be about 20-30 mm. When the neck is approximately the same size, the temperature of the outer jacket is uniform over the entire diameter of the hot roll.

As with the axial bore, an additional heat insulation sleeve 33 is also present in the radial bore 29, with an air gap 34 between the radial bore 29 and the additional heat insulation sleeve 33. This allows as much heat as possible to end up in the grooves. The air gap may be filled with fluid, but when the fluid in the air gap remains stationary, it acts like air as insulation. And therefore no sealant is required.

As previously mentioned, there is a central bore 25 in the journal 17. Advantageously, the starting point of the radial bore 29 is a flow splitter 35 arranged inside the central bore 25. The flow splitter evenly splits the flow of the heat transfer medium into the radial bores. Thus, even if the heat roller rotates at a high speed, the heat is uniformly distributed.

As shown in fig. 2a, both journals 17 and their conductors 18 are identical for conveying the heat transfer medium from one journal 17 to the other journal 17 via channels 22. Therefore, the heat transfer medium is fed from one end of the thermo roll and then is led out from the other end of the thermo roll. Alternatively, there may be a central tube 36 inside the central bore 25 and the journal 17, which serves for the supply or return of the heat transfer medium, as shown here. Thereby enabling the heat transfer medium to be fed in and out from one end of the thermo roll. This is illustrated in fig. 2a by the dashed line. There is also a stop 37 which closes the central bore 25 and feeds the heat transfer medium to the central tube 36.

Claims

1. A thermo roll for a fiber web machine, the thermo roll (12) comprising:

-a hollow roller body (13) having a plurality of grooves (14) on its outer surface (15), each groove (14) extending from one end to the other end of the roller body (13), and having an axial bore (16) in the roller body (13) leading to the groove (14);

-a journal (17) having a conductor (18) extending to the axial bore (16) and fixed to both ends of the roll body (13) by means of a plurality of bolts (19); and

-an outer jacket (21) which is friction-fitted on the roller body (13) and the shaft journal (17) and which outer jacket (21) closes the grooves (14) as a plurality of channels (22) for a heat transfer medium,

characterized in that each axial bore (16) has an offset (23) leading to two adjacent grooves (14).

2. Thermal roller according to claim 1, characterized in that each conductor (18) comprises a radial drilling (29) between two adjacent grooves (14), the corresponding axial drilling (16) being arranged to open into the radial drilling (29).

3. A thermo roll as claimed in claim 1 or 2, characterized in that there is a bolt (19) between two radial bores (29).

4. A thermo roll as claimed in any one of claims 1 to 3, characterized in that the axial bore (16) and the bolt (19) are on substantially the same radius with respect to the centre of the journal (17).

5. A thermo roll as claimed in any one of claims 1 to 4, characterized in that there are necks (24) between the grooves (14), at which necks the axial drillings (16) are located.

6. Thermal roller according to claim 5, characterized in that each bolt (19) is located at the neck (24) adjacent to the axial drilling (16).

7. Thermal roller according to any one of claims 1 to 6, characterized in that a heat insulating bush (31) is provided in the axial bore (16), with an air gap (32) between the axial bore (16) and the heat insulating bush (31).

8. A thermo roll as claimed in any one of claims 5 to 7, characterized in that the width of the neck (24) is the same as the width of the groove (14).

9. A thermo roll as claimed in any one of claims 1 to 8, characterized in that the depth of the grooves (14) decreases in the flow direction of the heat transfer medium.

10. Thermal roller according to any one of claims 1 to 9, characterized in that the thickness of the outer jacket (21) is 20-40 mm.

11. A thermo roll as claimed in any one of claims 1 to 10, characterized in that the wall thickness of the hollow roll body (13) is 60-80 mm.

12. Thermal roller according to any one of claims 1 to 11, characterized in that there is an additional heat insulating bush (33) in the radial bore (29), with an air gap (34) between the radial bore (29) and the additional heat insulating bush (33).

13. A thermo roll according to any one of claims 1 to 12, characterized in that a central bore (25) is provided in the journal (17), a diverter (35) being arranged inside the central bore (25) at the beginning of the radial bore (29).

14. A thermo roll as claimed in any one of claims 1 to 13, characterized in that both the journals (17) and their conductors (18) are identical for conveying a heat transfer medium from one journal (17) to the other journal (17) via the passages (22).

15. Thermal roller according to claim 13 or 14, characterized in that there is a central tube (36) inside the central bore (25) and the journal (17), which central tube is used for the feed or return of the heat transfer medium.